Method and apparatus for editing the output of a television set

ABSTRACT

In order to enable the editing of television programs in the home to exclude undesired sound or visual events (such as swearing or scenes of violence), these events are identified by coding inserted in the television signal prior to mass distribution. Preferably this coding is used to identify a range of possibly undesirable events, the coding including a grading of the events in terms of their undesirability. In the home, the coding is extruded from the received television signal by a suitable decoder. This coding is compared with a preset code identifying the grade or grades of event to be excluded; on the basis of this comparison the television signal is doctored before output on a television set. To facilitate following of the program being edited, only that portion of the television signal (sound or vision) carrying the undesired event is doctored.

The present invention relates to a method and apparatus for editing theoutput of a television set. In particular, but not exclusively, theinvention relates to a television controller which can be set by aperson in authority (such as a parent) to edit out undesired programmepart-contents (such as scenes of violence, or unpleasant language); thisediting can be carried out either in the television set itself or, inthe case of pre-recorded programmes, in the recording or playbackequipment.

Much has been written and said in recent years about the quality andcontent of broadcast television programmes. On the one hand, many peopleobject to the degree of violence and unpleasant language included inprogrammes while, on the other hand, the sensitivity of the broadcastingauthorities to accusations of censorship has made them reluctant toimpose standards in areas of programme content which are arguably amatter of personal preference.

Many parents while recognising the dangers of mass censorship, feel thatfor the good of their own children they must exercise a domestic editingfunction, by forbidding their children to view certain programmes whichthe parents consider unsuitable. Of course, such editing cannot preventchildren being subjected to unexpected bad language or violent scenes ofshort duration in programmes which are normally satisfactory from thispoint of view.

It is an object of the present invention to enable an editorial functionto be exercised over the output of a television, this editing functionbeing pre-selected by a person in authority (such as a parent ortelevison owner).

According to one aspect of the present invention, there is provided amethod of editing the output of a television set, including the stepsof:

(a) inserting into a television signal, prior to mass distribution,coding which individually identifies, as they occur, possiblyundesirable sound and visual events forming part of a programmerepresented by said signal, the coding indicating the sound or visualnature of each said event,

the method comprising the following further steps for implementationwhere it is desired, following mass distribution of said televisionsignal, to edit out from said programme at least certain of saidpossibly-undesirable events:

(b) monitoring the television signal to identify said coding,

(c) determining from the coding identified in step (b) the time ofoccurrence and nature of said possibly-undesirable events which are tobe edited out, and

(d) inhibiting the intelligible output, via said set, of the soundportion of said television signal when the determination effected instep (c) indicates the presence of a sound event to be edited out, andinhibiting the intelligible output of the vision portion of said signalwhen the determination effected in step (c) indicates the presence of avisual event to be edited out.

The method of the invention thus provides for editing out ofpossibly-undesirable events such as scenes of violence or bad language;this editing out is effectively at the discretion of the personreceiving the television signal since if the method steps (b) to (d) arenot implemented, the television signal will be output unedited.

The editing out can be effected by the complete deletion of the relevantsound or vision portion of the television signal or by the scrambling ofthis signal portion. Since the editing out of a sound or visual eventonly results in the inhibition of sound or vision as appropriate, themethod of the invention facilitates the following of a programme subjectto editing as compared to a method which involves the inhibition of thewhole television signal.

The method of mass distribution of the television signal can take anyform including normal broadcast transmission, cable networkdistribution, direct broadcast by satellite, and as a pre-recorded discor tape. The editing effected in accordance with the invention takesplace after this mass distribution but prior to the television signalbeing output via a television set. Thus the editing can take place inthe television set itself, during recordal on a video tape machine, oron output from a video tape or disc player.

The insertion of the coding will generally be done at the originatingtelevision studio. Of course, what constitutes an undesirable event isentirely subjective but generally for any given period in history, thereare certain matters which are offensive to a population taken as awhole, even though some individuals in that population may not concurwith the general view. Furthermore, certain events will be on theborderline, being found inoffensive by large sections of the populationbut still offensive to other sections. For this reason, the term"possibly undesirable events" has been used to refer to the type ofevent to be subject to coding.

Advantageously, the possibly-undesirable events are graded to permitediting according to personal taste. The lowest grading may be used toindicate a mildly offensive event only, whereas the highest grading mayindicate a highly offensive event. The person receiving the televisionsignal determines the grade or grades of event to be edited out; thus,for example, the predetermined code may be set to a mid-range grade sothat all events coded above this grade are edited out whereas thosebelow are allowed through. Setting the grading of undesirable events ispreferably effected independently for sound and vision.

The coding is preferably inserted into the television signal in thefield blanking period and may take the form of one or more digital datawords. The techniques required to insert data into a television signalin this manner are well known to persons skilled in the art, sinceteletext services generally operate on this principle (thus, forexample, the Ceefax service provided by the British BroadcastingCorporation is of this form). In one preferred embodiment of theinvention, the coding is, in fact, constituted by the row numbers of aparticular page of a teletext service, the page number and relevant rownumber being transmitted in the next occurring field blanking periodupon the occurrence of a possibly offensive event. At the receivinglocation, a teletext decoder is permanently set to look at the relevantpage and identifies each row number as and when transmitted, theparticular row numbers indicating particular gradings of sound andvision events.

The identification of an undesired event is preferably used to blanksound or vision, as appropriate, for a given time period of, forexample, 1/2 second so as to avoid the need to continually insert thesaid coding throughout the duration of a possibly undesirable event. Ifan event lasts longer than this time period, then the relevantidentifying coding is inserted again just before the end of this period.

The generation and insertion of the coding into the television signal atthe correct time is no great problem for programmes which are nottransmitted live since the programme can be viewed on a video tapemachine and the start of each event accurately determined using theframe hold and rewind capabilities of such a machine. However, theinsertion of coding is clearly less easily effected where "live"programmes are concerned. One possible way of coding "live" programmesis to feed the television signal through a delay (for example, of 2seconds duration) during which time a monitoring operator views thetransmission and adds the coding as appropriate.

According to another aspect of the present invention, there is provideda controller for editing out undesired sound and visual events from atelevision signal where this signal includes coding individuallyidentifying, as they occur, certain possibly-undesirable events formingpart of a programme represented by the signal, the coding including anindication of the sound or visual nature of each such event,characterised in that the controller comprises:

monitor means for monitoring the television signal to identify saidcoding and output a corresponding coding signal,

signal processing means connected to receive said coding signal andarranged to determine therefrom the time of occurrence and nature ofsaid certain possibly-undesirable events, these latter events beingevents which are to be edited out, and

inhibit means arranged to operate on said television signal such as toinhibit the intelligible output from said controller of the soundportion of said television signal when the signal processing meansindicates the presence of a sound event to be edited out, and to inhibitthe intelligible output from the controller of the vision portion ofsaid television signal when the signal processing means indicates thepresence of a visual event to be edited out.

Television edit-coding apparatus and a television receiver editcontroller, both embodying the present invention, will now be described,by way of example, with reference to the accompanying diagrammaticdrawings, in which:

FIG. 1 is a block diagram of a prior art television receiving setprovided with a standard teletext unit;

FIG. 2 is a representation of parts of two lines of data of a standardteletext transmission; and

FIG. 3 is a block diagram of the edit coding apparatus and the editcontroller.

The method and apparatus to be described hereinafter provide for theautomatic editing of a television programme in the home in order todelete from the programme various grades of undesirable sound and visualevents, the selection of the grades of event to be edited out beingeffected by a person in authority, such as a parent. This editingprocedure is based upon the insertion into the television signal, priorto its mass distribution, of a coding which identifies the presence of arange of possibly undesirable events in the programme represented by thesignal. The inserted coding is used to identify the grade ofundesirability of each particular event as it occurs and also its soundor visual nature. On receipt of the television signal in the home, thesignal is monitored to identify the aforesaid coding and edit out fromthe television signal each sound or visual event the grading of whichindicates that it is of a type which the person in authority does notwish to be output.

In the embodiment of the invention to be described, the codingindicating the presence of possibly undesirable events takes the form ofthe row addresses of a particular page of a teletext signal carried bythe television transmission. To enable a clear understanding of thedescribed embodiment, a brief description will therefore first be givenof a suitable teletext system such as the Ceefax service provided by theBritish Broadcasting Corporation.

In the Ceefax teletext service which is used with a 625 line televisionstandard, digital data is added to the television signal during twolines of each field of the signal. These two lines are chosen to occurduring the field blanking period which is typically of 25 linesduration. More particularly, lines 17 and 18 of the first field of aframe and lines 330 and 331 of the second field may be used for theteletext data. Four lines of data are thus transmitted in each framegiving, for a frame repetition rate of 25 frames per second, a data linerate of 100 lines per second.

Each teletext data line corresponds to a row of data for display. Forconvenience of operation, the data rows are organised into "pages" oftwenty four rows, each page being intended to be displayed whole. To aididentification and selection of required data, these pages areconsidered as being organised into "magazines" of one hundred pages.Typically eight magazines may be provided in a teletext service. Ofcourse, a single insertion of all possible data rows into the televisionsignal takes a substantial amount of time (around three minutes);however, in practice, the most commonly required data is inserted atmuch more frequent intervals.

FIG. 1 shows in block diagram form a television receiver selectivelyoperable to display teletext data. The receiver comprises standard RFand IF receiving circuits 10 which output video and sound signals onlines 11 and 12 respectively. The video signal is fed to asynchronisation circuit 13 of the receiver and, via a gate 14, to avideo circuit 15 the operation of which is controlled from the circuit13. The output of the video circuit 15 is fed to a television tube 16.The sound signal from the receiving circuits 10 is fed, via a gate 17,to a sound circuit 18 used to drive a loudspeaker 19.

The operation of the gates 14, 17 is controlled by a teletext selectunit 20, these gates being enabled to permit normal operation of thetelevision receiver whenever the teletext service is not required.

To display a particular page of teletext data, the select unit 20 isoperated to inhibit the gates 14 and 17 and enable a teletext decoder 21of the receiver. This decoder 21 receives the video signal from thereceiving circuits 10 and picks out from this signal the teletext dataincluded therein. A detailed description of how this is achieved willnot be given herein since the techniques involved are well known.

The select unit 20 is used to specify the page of teletext data requiredto be display. The decoder 21 monitors the received data and stores therelevant page of data when received, this data being held in store 22.The stored data is accessed by a character generator 23 which operatesto generate a video signal providing for the alphanumeric display of thedigital data held in the store 22. This video signal is fed to thecircuit 15 whereby the selected page of data is displayed on the tube16.

To enable the decoder 21 to identify the data to be displayed, it is, ofcourse, necessary for the teletext data carried by the television signalto be appropriately marked with its magazine and page number.Furthermore, each row of data is marked with the corresponding rownumber to facilitate reconstitution of the relevant data page.

FIG. 2 shows in diagrammatic form the make-up of the initial portions oftwo data rows, the upper row corresponding to the first or "header" rowof a page and the lower row corresponding to any one of the other twentythree rows of a page.

Each row is made up of 45 data bytes. In the header row, 32 of thesebytes represent data for display whereas in the remaining rows 40 bytesare assigned to this task (in FIG. 2 the bytes containing data fordisplay are marked with a diagonal line). Of the remaining bytes in eachrow, the first three (marked S) contain synchronisation informationwhile the fourth and fifth bytes (marked MR) indicate the magazinenumber and row address of the particular data row concerned. In theheader row only, the sixth and seventh bytes (marked P) contain pagenumber information, bytes eight to eleven (marked T) contain timeinformation and bytes twelve and thirteen (marked C) contain controlinformation.

Returning to a consideration of the present invention, in the embodimentto be described the possibly objectionable events in a televisionprogramme are divided into eight categories, namely four gradings ofpossibly objectionable sound events and four gradings of possiblyobjectionable visual events. For ease of reference, these categorieswill hereinafter be referred to as GS1 to 4 for the sound event gradingsand GV1 to 4 for the visual event gradings. Each event category isarranged to be represented by a corresponding coding enabling both thesound or visual nature and the grading of the event concerned to beidentified. In the present embodiment, these codings are constituted byrespective row addresses of a predetermined page of a teletext service;for convenience, these row addresses will be referred to by the eventcategory which they designate (thus, for example, reference to rowaddress GS2 is intended to mean that row address which represents thepresence of a sound event having a grade 2 of undesirability).

FIG. 3 illustrates how these row address codings might be generated inthe case of a programme being transmitted live. The output of a camera30 and of a microphone 31 are passed through respective processingcircuits to produce standard vision and sound signals. These signals arefed to a monitor station 33 and via a delay 34 to a mixer 35. At themonitor station 33 an operator watches and listens to the programmebeing made in front of the camera 30 and microphone 31. On theoccurrence of a possibly undesirable sound or visual event, the operatorpresses an appropriate key to indicate the presence of such an event andalso its nature and grading. The operator keeps the relevant key (orkeys where both possibly undesirable sound and visual events occurtogether) pressed throughout the duration of the event concerned. Thepressing of a key results in a teletext unit 36 inserting into thecomposite television signal produced by the mixer 35, the appropriaterow address coding indicative of the nature and grade of event noted bythe operator. The coding is inserted during the next-occurring fieldblanking period by the inclusion of a teletext data line correspondingto the header row of a page. The inserted data line thus contains notonly the row address coding but also the appropriate magazine and pagenumber identifying the row address as one related to the editing out ofundesired events.

The purpose of the delay 34 is to delay the vision and sound signals fora period corresponding to the approximate reaction time of the operatorso as to ensure that the event codings are inserted into the compositetelevision signal substantially in synchronism with the sound or visionsignal representing the event coded.

The composite television signal produced by the mixer 35 is fed to atransmitter 37 feeding an aerial 38.

Where the teletext unit 36 is used to transmit a normal teletext serviceas well as the event codings of the present invention, the insertion ofan event coding will, of course, interrupt the normal sequence ofteletext data transmission. After the insertion of each event coding theunit 36 is arranged to commence the re-transmission of any data pageinterrupted, Furthermore, as will become clear hereinafter, the presentembodiment of the invention is so arranged that it is not necessary toinsert an event coding during each field blanking period occurringduring the concurrency of a possibly undesirable event; as a result, theinterruption of the normal teletext service by the insertion of eventcoding is minimal. Of course, the unit 36 could be dedicated to thetransmission of event codings, the normal teletext service being omittedentirely.

Shown in the lower half of FIG. 3 is a television receiver provided withan automatic edit controller embodying the present invention. The FIG. 3receiver, like that of FIG. 1, comprises receiving circuits 10outputting video and sound signals, on lines 11 and 12 respectively, tocircuits 13, 15 and 18 supplying vision and sound signals to atelevision tube 16 and loudspeaker 19. Gates 14 and 17, provided in thelines 11 and 12 respectively enable the vision and sound signals to beselectively blanked.

The edit controller associated with the television receiver of FIG. 3comprises a teletext type decoder 40 arranged to continuously monitorthe video signal on line 11 to identify from the received teletext dataany row addresses indicating the presence of a possibly undesirableevent in the programme currently being receive. To this end, the decoder40 is fed from a memory unit 41 with the predetermined magazine and pagenumber identifying the teletext page whose row addresses are indicativeof the event categories GS1 to 4 and GV1 to 4. Upon the recoder 40identifying a row address coding on the relevant teletext page, thisaddress coding is immediately output to a comparator 42 or 43, thecodings GV1 to 4 being output to the comparator 42 and the codings GS1to 4 to the comparator 43.

The grade or grades of sound and visual events that it is desired toedit out are set in using an edit select unit 44, access to this unitbeing restricted by the provision of a lock 45 which may be mechanicalor electronic. The unit 44 is arranged to output to the comparator 42the least undesirable grade of visual event it is required to edit out;in addition, the unit 44 outputs to the comparator 43 a code indicatingthe least undesirable grade of sound event to be edited out.

Upon an event coding being fed to the comparator 42 which is equal tothe code supplied thereto by the unit 44 or represents a moreundesirable visual event than that code, the comparator 42 outputs anedit pulse which is expanded by the timer 46 into an inhibit signal offixed duration (for example 1/2 second duration). This inhibit signal isfed to the gate 14 and is used to block the video signal from receipt bythe circuit 15. In a similar manner, when the comparator 43 receives anevent coding indicating a sound event which is of equal or greaterundesirability than that represented by the code from the unit 44, thecomparator 43 outputs an edit pulse which is expanded by a timer 47 intoa 1/2 second inhibit signal controlling the gate 17 in the sound signalline 12.

In this manner, the sound and vision signals are selectively blankedupon the occurrence of a grade of sound or vision event which it isdesired to edit out.

The presence of the timers 46 and 47 means that it is only necessary toinsert an event coding at the beginning of each event and thereafter at1/2 second intervals (or slightly less) during the currency of theevent. This feature enables normal teletext services to be provided bythe transmitting station with only minimal interruption due to theinsertion of event codings.

If desired, while the sound and/or vision is being blanked, a messagecan be displayed on the tube 16 indicating the reason for the blanking.In the embodiment illustrated in FIG. 3, this message is derived fromdata contained in the data row carrying the event coding causing theblanking, this character data being extracted by the decoder unit 40 andpassed to a message display control unit 48 over a line 49. The unit 48includes a character generator and various control circuitry which inthe presence of an inhibit signal from the timer 46 or 47, causes anappropriate video signal to be fed to the video circuit 15. This videosignal is arranged to display a message on a restricted portion of thetelevision screen since, of course, the vision signal may still be openfor display. In this latter case, to avoid the simultaneous presentationof the normal vision signal and a message from the unit 48, this unit isarranged to inhibit the vision signal, using the gate 14, during theportion of each television field corresponding to the area of the screenwhere said message is to be presented.

The edit controller shown in FIG. 3 has been described in relation tobroadcast television transmissions received from one transmittingstation. However, of course, the edit controller will operate to effectautomatic editing of a television signal regardless of its sourceprovided that the event coding is inserted into the television signal ina standard manner (in the present case, on a predetermined page of ateletext format). Furthermore, the edit controller need not necessarilybe provided as part of a television receiver but can be included at theinput or output of a video tape recorder or at the output of a videodisc player. It will also be appreciated that the described form ofevent coding is only one of a number of possible ways in which suchcoding can be inserted into a television signal, although it ispreferred to utilise a teletext type of coding due to the availabilityof teletext decoding integrated circuits. Of course, while it ispreferred to insert event codings during field blanking periods of atelevision signal, this need not necessarily be the case, particularlywhere the format of the television signal allows data to be insertedduring any line period (such as may be the case with digitally encodedsignals for use in satellite broadcasting).

Various other modifications are of course possible to the editcontroller illustrated in FIG. 3.

I claim:
 1. A method of providing for the editing of the output of soundand visual portions of a television set, comprising the steps of:(a)inserting into a television signal, prior to mass distribution, codingwhich individually identifies, as they occur, possibly undersirablesound and visual events forming part of a programme represented by saidsignal, the coding indicating the sound or visual nature of each saidevent, (b) monitoring the television signal to identify said coding, (c)determining from the coding identified in step (b) the time ofoccurrence and nature of said possibly-undersirable events which are tobe edited out, and (d) inhibiting the intelligible output, via said set,of the sound portion of said television signal when the determinationeffected in step (c) indicates the presence of a sound event to beedited out, and inhibiting the intelligible output of the vision portionof said signal when the determination effected in step (c) indicates thepresence of a visual event to be edited out.
 2. A method according toclaim 1, characterised:in that the said coding inserted into thetelevision signal is used to identify a range of events of varyingdegrees of possible undersirability, the coding including a gradingindicating the degree of possible undesirability of each said event, andin that step (c) involves comparing the event grading included in thecoding identified in step (b) with a predetermined code indicative of anundesired grade or grades of event, the result of this comparison beingused to identify the events to be edited out in step (d).
 3. A methodaccording to claim 1 or claim 2, characterised in that said coding isinserted into said television signal as a teletext type signal.
 4. Amethod according to claim 3, characterised in that said coding takes theform of one or more row addresses of a predetermined teletext page.
 5. Amethod according to claim 1, characterised in that said coding isinserted into the television signal by passing the signal through afixed time delay while an operator views and listens to the programmerepresented by the signal and inserts a suitable said coding upon theoccurrence of a said possibly-undesirable event, the time delay servingto compensate for the non-instantaneous reaction of said operator tosuch an event.
 6. A method according to claim 1, characterised in thatcoding identifying each possibly-undesirable event is onlyintermittently inserted in said signal during the event, and in thatinhibition of the sound or vision portion of said signal, following eachdetermination of the occurrence of an event to be edited out, iseffected for a predetermined time period which is of greater durationthan the interlude between successive insertions of coding identifyingthe event.
 7. A method according to claim 1, wherein during theinhibition of a said portion of the said television signal, a videocharacter signal is added to the said television signal to provide avisual display, at said set, indicative of the reason for saidinhibition.
 8. A controller for editing out undesired sound and visualevents from a television signal where this signal includes codingindividually identifying, as they occur, certain possibly-undesirableevents forming part of a programme represented by the signal, the codingincluding an indication of the sound or visual nature of each saidevent; said controller comprising:monitor means (40) for monitoring thetelevision signal to identify said coding and output a correspondingcoding signal, signal processing means (40,42,43,44) connected toreceive said coding signal and arranged to determine therefrom the timeof occurrence and nature of said certain possibly-undesirable events,these latter events being events which are to be edited out, and produceinhibit signals in response thereto and inhibit means (14,17) arrangedto operate on said television signal in response to said inhibit signalssuch as to inhibit the intelligible output from said controller of thesound portion of said television signal when the signal processing means(40,42,43,44) indicates the presence of a sound event to be edited out,and to inhibit the intelligible output from the controller of the visionportion of said television signal when the signal processing means(40,42,43,44) indicates the presence of a visual event to be edited out.9. A controller according to claim 8, intended for use where said codingis used to identify a range of events, including said certain events, ofvarying degrees of possible undesirability, the coding including agrading of each said event, characterised in that said signal processingmeans comprises:selection means (44) enabling an operator to set in thegrade or grades of event to be edited out, the selection means (44)being arranged to store a grade signal representative of the set ingrade or grades, and comparator means (42,43) for comparing the saidcoding signal with the said grade signal whereby to determine whichevents are to be edited out by said inhibit means (14, 17).